Looks like you should try something without a daggerboard. Either the GO or Futura boards would work well. If you really are looking for higher performance, the Futura is lighter (about 2kg) for the same size GO, a little narrower and will be more resposive (more fun in the long run). However, if you only sail occasionally and aren't big into higher performance and faster speeds, the the GO may be a better option. GO's can go pretty fast, it just takes a little more power because of their weight.
Since your winds are generally light and you weigh 200 lbs, you might think about the 155. If you are comfortable planing and in the straps with the dagger board up on the Rio, then the 144 may be a better choice for the stronger winds.
Others may have some other suggestions. Hope this helps. There is never one best answer because so much depends on your drive and dedication to windsurfing as well as where you live and the prevailing conditions.
You might run your question by Roger in the "Windsurfing School" Forum. He is an expert with guys at your level of sailing.
Last edited by Ken; 18th February 2009 at 12:28 AM.